A Ribbon of Life Through the Concrete of Houston

Flood Bond Election: New Projects Added

Tensions on Buffalo Bayou

August 19, 2018

The Harris County Flood Control District presented to Harris County Commissioners Court Tuesday, Aug. 14, its final list of flood risk reduction projects that could be funded with the proceeds of $2.5 billion in bonds over a period of 10-15 years.

These include $30 million for design and construction of replacement bridges along Buffalo Bayou, apparently targeting bridges that went under water during Harvey or are thought to be obstructing the flow.

The new list includes $500,000 for studies to investigate “bridges over Buffalo Bayou, the channel conveyance capacity around Beltway 8, Rummel Creek Road bridge and potential high flow bypasses at various locations along the bayou for the purpose of reducing the risk of flooding along the channel.”

Also newly included is $200,000 for investigation of the “effectiveness of small detention sites in the Buffalo Bayou watershed for the purpose of reducing the risk of flooding.”

Rivers and streams are dynamic systems, evolving through the landscape to find equilibrium, balancing energy, flow, and sediment transport. While meandering streams carry more water because they are longer (p. 9), artificially straightening streams shortens the channel and increases the speed of the flow, which can cause more erosion and flooding. (See below.) Meandering streams are more stable, healthier, cleaner, and more biologically diverse. (p. 2)

Some six miles of Buffalo Bayou below Barker Dam was rerouted, stripped, and straightened in the late Forties and Fifties by the Corps of Engineers through what is now Terry Hershey Park to several hundred feet below Beltway 8. Environmentalists, including Terry Hershey, Frank Smith, George Mitchell, and others, many of whom also lived on the bayou, led a popular movement in the Sixties and Seventies to stop the Corps from stripping, straightening, and concreting the bayou all the way to the Shepherd Bridge.

A comparison of the original meanders and the straightened channel of Buffalo Bayou flowing through Terry Hershey Park by geologist Tom Helm.

As a result, much of Buffalo Bayou remains in a relatively natural, meandering state.

In the interim, however, subdivisions were built along and on top of the former channel and remaining oxbows of the straightened section of Buffalo Bayou in what is now Terry Hershey Park, now owned by the flood control district. A great many homes flooded in these subdivisions, along with other residences up and down the bayou.

Harris County Flood Control District projection of flooding along Buffalo Bayou on Aug. 29, 2017, following releases of stormwater from the federal dams. Note that this is a map of flooding from the opening of the floodgates Aug. 28 after the initial peak of Harvey flooding had passed downstream on Aug. 27. Compare this map of flooding on the straightened artificial channel above Beltway 8 with the above map of the original meanders.

Though Huffmaster, whose house flooded on a remnant oxbow of the bayou adjacent to Terry Hershey Park, claims in his proposal that “east of Piney Point, few structures flooded even at 16000 cfs [cubic feet per second],” (p. 15) anecdotal reports from residents downstream are that entire neighborhoods had anywhere from a foot to as much as eight feet of water in their homes all the way to Shepherd Bridge. Residents upstream and downstream describe the peak of the Harvey flooding beginning the morning of Sunday, Aug. 27, and passing that evening downstream. However, in response to the unprecedented amount of rain runoff flowing into the reservoirs, the Corps of Engineers was forced to begin controlled releases from the dams around 1 a.m. Monday, Aug. 28. This precipitated a second wave of flooding primarily hitting those upstream neighborhoods closer to the dams, including some that hadn’t flooded earlier. Many of those devastated neighborhoods, as well as neighborhoods all over the county, are still attempting to recover even as voters go to the polls.

The district report describes the four-day total rainfall from Harvey, Aug. 25-29, 2017, in the larger Buffalo Bayou watershed, as well as in the majority of Harris County, as an event so large it should only occur once every 5,000-20,000 years. Southeastern Harris County’s four-day rainfall is described as a 20,000-year-plus event. (p. 30)

Not included is addressing the problem of massive stormwater outfalls pointing directly across the bayou, of which there are several in Terry Hershey Park including at Beltway 8. Stormwater drainage pipes perpendicular to the stream block the flow and are in violation of the flood control district’s design manual. (p. 111)

Big drain pipe on south bank sends water directly across Buffalo Bayou in Terry Hershey Park, acting as dam during storms. Photo October 2015.

The list also includes funds proposed to be used in collaboration with Army Corps of Engineers, which owns and operates Addicks and Barker, to evaluate the effectiveness and operation of those 70-year-old dams.